Cooking ranges having ventilated surface units are well known in the prior art. One such range, with interchangeable surface elements, is disclosed in, among others, Cerola U.S. Pat. No. 3,797,375. Convected, or forced circulation ovens are also well known, these having the advantage of more efficient and rapid heat transfer to the food in preparation. This results in substantial energy saving and reduces meat shrinkage. To the present convected ovens have been used in institutional and commercial baking and have not been found in domestic ranges because of the long-established commitment to radiant type ovens and the design difficulty and customer resistance inherent in a change from the long-established radiant oven mode of operation.
The concept of the present invention envisages the adaptation of the ventilated surface unit type of range, disclosed in the patent mentioned above, for convected oven mode of operation. The oven can be operated, if desired, in the conventional radiant mode and, in the preferred form, utilizes the conventional lower oven baking element and the conventional, upper broil element without requiring the addition of special heating elements for the convection mode operation of the oven.
With the additional air passages formed in the oven to provide the convection oven option, and by providing for forced circulation of air within the hollow oven door (as contrasted to thermal convection of cooling air within the oven door), the oven may be operated at elevated temperature (of the order of 550.degree. F) for a time interval without producing an unacceptable temperature rise on the outer surface of the oven door and adjacent frame and top surfaces of the range. This freedom to operate the oven at elevated temperature provides an important advantage. "Catalytic" type self-cleaning ovens have, in the recent past, achieved considerable market acceptance. A catalyst is added to the porcelain frit which covers the interior surface of the oven and, through its action, during normal oven use at normal temperatures, the heat, oxygen and the catalyst combine to remove and oxidize grease and spattered particles from the oven walls during use. The cleaning action occurs while the oven is in regular use and is referred to as "continuous cleaning". It has been found that debris removal performance at normal oven operating temperatures leaves much to be desired. However, if the oven can be safely operated at an elevated, 550.degree. F, temperature for a cleaning cycle time interval of one to three hours, soil removal performance is vastly improved.
The structure of the present invention provides a passage adjacent the upper, insulated surface of the oven which, through apertures adjacent the surface heating elements, communicates with the ventilating plenum and, at the other end of the passage, communicates with apertures which generally register with apertures along the upper margin of the oven door. When the oven door is closed, cooling air is thus drawn through the oven door into the passage above the oven and then into the ventilating plenum. This cooling of the door and range surfaces adjacent the passage limits the temperature rise of these surfaces and permits operation of the oven in a cleaning cycle at high temperature for the desired time interval to provide the enhanced soil removal performance inherent in the high temperature, cleaning cycle operation.